Page 242 - Carbon Nanotube Fibres and Yarns
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232 Carbon Nanotube Fibers and Yarns
ρ(T) measurements on a composite fiber stretched by 53% and an annealed
one stretched by 76% displayed in Fig. 9.9B shows that ρ for the composite
fiber exceeds that of the annealed one by four to five orders of magnitude
at 300 K. This suggests that not just the morphology of the two fibers but
the conduction mechanisms in the two morphologies affects their ther-
moresistive properties. Le et al. [8] determined the thermoresistive response
of the free CNT yarns and the CNT yarns integrated in a polymer matrix
subjected to heating and free cooling cycles (Fig. 9.10). The thermoresis-
tive behavior of a selected sample under three heating/cooling cycles as
Thermocouple
Fluke 298 Sample Oven’s
heating plate
T(°C)
Agilent 34411A
R(Ω)
(A) Data acquisition
1 1
Sample #1 - cycle 1
0 Linear fit 0
−1 −1 (∆R/R 0 ) res
−2 −2
∆R/R 0 (%) −3 −2 ∆R/R 0(%) −3 Hα (∆R/R 0 ) max
−4
−4
−5 α∼−2.34×10 −5
−6 −6
−7 −7 Sample #1 - cycle 1
−8 −8
0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 350
(B) ∆T/T 0 (%) (C) ∆T/T 0 (%)
Fig. 9.10 (A) Schematic representation of the thermoresistive measurement system
[8]. (B) Linear fit of CNT fiber monocomposite sample during first heating section.
(C) A hysteretic cycle showing the parameters obtained from the thermoresistive
characterization [8]. (Source: H.H. Le, G. Brodeur, M. Cen-Puc, J.J. Ku-Herrera, F. Avilés, J.L.
Abot, Piezoresistive and thermo-piezoresistive response of constrained carbon nanotube
yarns towards their use as integrated sensors, in: Proceedings of 31st American Society for
Composites Conference, Williamsburg, VA, 2016.)